Creating a sweepstake type db

Hi,

I was just wondering if someone could please point me in the right direction of how to design a database I need.

We have this thing in Australia called the Melbourne cup and work sweepstakes are very big on this day.

The key points to the database would be

1. horse names

2. staff names

3. share values

Each person can have as many shares as they like. The types of shares will be $1, $2, and $5.

So for example if there are 15 horses running, and there are 3x$1, 2x$2 and 1x$5 there are effectively

45 x $1 records

30 x $2 records

15 x $5 records

Lets say someone purchase 3x$1, 1x$2 and 1x$5 being a $10 payment.

I would then need to run a script to randomise it and select 5 of the horses names, remove them from the pool.

I'm just having trouble understanding if a) this is possible and : how I would go about such a thing.

I attach an excel list to show as an example of what is the end product from last year (this was produced manually).

I've worked out my basic tables but the rest :

Melbourne_Cup_Sweeps.zip